The present invention relates to an assisted braking device comprising a master piston mounted to slide in a master cylinder, a jack having a piston linked to the master piston by interconnecting means, a source of auxiliary hydraulic pressure, and a distributor which is suitable for feeding the jack with auxiliary hydraulic pressure from the said source and is controlled in response to the actuation of control means comprising a pedal and two mutually articulated levers, in which device the unit consisting of these two levers cooperates with a fixed point and has three working points of which the first cooperates with the pedal, the second cooperates with the distributor and the third cooperates with the master piston.
Compared with the devices with a single lever, these devices with two levers exhibit the advantage that they make it possible to choose an optimum step-down ratio, in particular in the event of failure of the auxiliary system, whilst at the same time satisfying other desirable conditions of construction and operation and in particular the extremely desirable condition of small size.
In general, in these devices with two levers, the working point cooperating with the pedal, and the fixed point, are located on one of the two levers, whilst the working point cooperating with the distributor and the working point cooperating with the master piston are located on the other lever. As a result, a large number of articulations are involved in the control of the distributor by the pedal.
The present invention relates to an assisted braking device of the type indicated above, which does not suffer from this disadvantage and in which the control of the distributor by the pedal is direct and hence precise.